



3 serves as an anode potential supply source, the positive terminal o! the battery being connected through a lead 2l to the wave guide structure. The potential of the battery 22 is preferably adinstable. The wave guide, plates II, I2 and I3, the resonator I4 and the constricted intermediate section Ii are all oi' metal oi' high conductivity or havahighiy crdnotive surtaces where exped within the vacuum tight system. All the metal parts exclusive of the cathode and heater are connected together in good electrical contact and the whole structure is made vacuum tight.

As the means of insuring a substantially pure traveling wave in the interior; oihdihemetallic structure, a resistor 24 is provided between the end plate Il and the nearest bane-plate II. The resistor 24 is preferably in the .toi-m n! lltpost, rod, wire or other like structure and is .composed oi material of relatively high resistivity.

An input coaxial line is provided having an iimm conductor Ikon outer conductor 26, .the :inner conductor 2l yterminating in a coupling hop 21 'which enters an opening in the pipe I0 thrown an insulatim'and sealing bushing 2t.

in output-coaxial line is provided having an .inner conductor ll md an outer conductor 30. -with:the.inner conductor terminating in. a -cou- 8| inside .the fresonator Il, entering v-Iihrough an insulating and sealing bushing 32. YIheouter conductors Il and I8 are conductively to :the pipe Il and the resonator Il, respectively. .In Aaccordance with ordinary practice-mid as an additional measure to minimize -iladted waves. the-characteristic impedances of thciines :RL 2l and. Il, l. are matched tothe.

-ahacacteristic impedance of the respective wave 'guides to which .thezlinea are colmeeted.

Broken lines parallel tothe central axis-oi the device indicate the approximate limits ot the electron heampath extending irom the face.

AIl-olthe cathode to the inner wall oi the resonator I4 throum -the aligned :central apertures imtheplates M.. l2 and It. the oonstricted wave guide It and the aperture in the resonator. Electrons may -be'drawnztrom the cathode tace .il by virtues! the potential diiierence between the cathode aldthe anode structure comprising the-.metti parttoxolusive o! the cathode and fuitable provision may be made for focusing the flieam viii-order to constrain the 'mr portion o! the electrons to remain withinftheriimits-oi the path Ilysuoh means. being -nllknownin the art and comprising. for .ex- Amultiuso. :iomingfcoil 1t and a battery 1li :or

-ie .directional the-path .88.

'Tin Nie operation Yof the device of Fig. i, the Aspeed 10iy -the electrons along .the direction of the path' It vmail be adjusted to be substantially innalzato the speed of. propagation of electro- -magnetic waves alms the same path. The baille 1I are-use1ul in bringing about -a sub- -stantialeqw1ityfofspeeda the plates producing .a structure in the nature oi an inductively loaded line. :the speed ci' propagation along which may hmndmed tofarraotion oi thespeed oi propagatiomoi eleco waves-in tree space. It is known that the wares in iree space travel with 'subsmntially light and that elec- `mains-.inelection'.beams produced by means oi .muy convenient voltages are oi `the order `nhngnitude n! one-tenth the spoed of light and less. to the voltage. By suitable design .cime wave guile do and plates II thespeed of zwopaaatixmot waaesa'hmg the path )I may be 4 brought within easy reach of the adjustment of electron speed available by varying the potential of the battery 22. The resistance value of the resistor 2l is adjusted to be as nearly as possible an exact impedance match for the loaded transmission line structure comprising the wave guide I0 and the plates Il. Electromagnetic waves hnprelsedopcnthe input coaxial .line t5, 25 are propagated through the wave guide IiiV and absorbed in the resistor 24. The object of this arrangement is to provide a pure traveling wave in the wave guide I0 with no appreciable reilection oi the wave from the end plate I3. Wave imctionsi'romftheend plate I2 are minimized bythe matching at the junction with thcline NAB.' :.'Ihe traveling waves progressing .immlleit to .right through the wave guide Il react upon the electrons from the cathode tace "f8 and; "oy virtue of the equality of speeds, the

-ilarto that fit-thc device oi Fig. 1.

electrons progress along the wave guide keeping suhstantiallyahreast of the electromagnetic waves. .Electrons which enterthe region ofthe -xvavainthe 1roller phase to absorb energyiram the wave are.. continuously accelerated by the wave and other electrons entering in the proper phase to..deliver energy to the wave are Aie celerated. As long as the changes of speed of the electrons remain small in comparison with the initial electronspeed produced by the potentialot the battery 22, the electrons whichare speeded up continue to be so ailected throughout .the lemth. oi the guide I0 and the electrons which are .slowed down likewise are sov adected continuously .throughout their transit of .the guide. Electron bunching occurs due tothe tact that theaccelerated .electrons tend to overtake those whicharedecelerated. .The result .is that `the electron stream upon altering the constricted section ills. characterized by electron density variations. .In other words .there is a tendency tor the yeloctronsizo become grouped ln bunch separatedby spaces containing reiativelyiew electrons. Further bunching o! the electrons may occur during their `passage through the section i5. Upon entering the interior of the resonator Il. the bunches of electrons induce alternating electric currents in the inner surfaces o! the resonator in well-known manner. In other words, the electrons excite the resonator into oscillation. An output of oscillations in the form or an electromagnetic wave is impressed upon the output coaxial line n, l0 by means of the coupling loop II. The impressed wave upon'tm 'input coaxial line 25, 2l is not transmitted to lthe output coaxial line 2l, 20 but is absarbediin the resistor Il, or is suppressed in the intermediate wave guide vsection I5. which may beni such small diameter that it will notireely propagate leletio waves of Vthe frequency or lfrequencies imd upon the input line.

The: device .of Fig.. 2 is similar to that o! Fig. l except fthat ythe resonator I4 is replaced by a section of loaded transmission line Il with baille plates Il 'similar to the wave guide i0 and plates 4I I, respectively. The electron path passes through the. central apertures and the .constricted intermediate section I5 substantially as in Fig. i. The wave guide Il has terminating end plates 42 and 43, respectively, and a resistor is connected between the end plate 42 and the next plate 4I. 'I'he output coaxial line 28, It has kits inner conductor connected to the .end plate n.

The operation o! the device of Fig. 2 Is sim- The eleoimvooi fingieaergyirmn the electrons oi the besmsand MM in mmmmfer relation thereto. initurmonbxrnearest the cathode for modulating said beam .in-accordance with -emleiimmemin said .initial portion, and hav- 'zinaiafnnal portion more remote from said cathtrom'the beam so clciillatsmmeans to the-said initial filter portion to impre waves of a band of'frequencies to be amplled on said inithlrlter portion at thereof-Mds nearect the cathode, said *mi r-means: being matched to said nmcture inrmipedanee over substantially missie of said frequency band and an output r circuit for mpliedwaves connected to sald'nal 'ziiltnrlntion at-thaend'therecf that is most re- :mllntnm `the cathode, said output circuit lbe- .I'Jlilentdied .tosaid lter structure over-substanlllyllhc-whole; of said frequency hand, the .mrnlterpertion workinglnto a succeeding :titer portion, `*saidwportions being matched as .lockingin the direction awayifrom .itin portion edtstaporticnasaid final portion and rimltfprecedingmftion being matched aste impednice 'ffl'. amd :band electrical amplifier comprisdngursonrcefclcharged particles, projecting #moans @forming particles from said source into .im a'inndwass nlter structure of elongated -hmrextendhg lmgthwise along the path of the mummia energy transferrelatlon there- .inrlaldllter having 1m initial portion `nearest thspsojeeting-mems dor modulating said beam 'in aceordamewith traveling waves in said initial a nml portion more remote man midproieetingmeans'inwhmhswaves may lkindisch!!'hy'thisheainl so modulated, means '-medto the saidinitial filter portion to imof the band of frequencies-to bei.V

- hpon'nald initial' titer portionv at the zendlthexeof thatis nearest-the projecting means, :nhifwave g means having its imped- Myequal to the characteristic impdahce bf oversubstantiaily the whole,

-of'the frequency pass band of the iliter and a idelrcuit tor-induced waves connected to said 'Militar porttonat the end thereof most re- -mcte trom said projecting means, said load circuit having'itsimpedance substantially equal to the diaracteristicmpedance of the filter. over -subdzantially the whole of the pass band, the mithi--nltsrpcrticnfaeing a matched Vtermination in the filter structure looking away from the projection means and the'ilnal mter portion. E

nearest the said beam projecting means in energyv` transfer relation to the beam for bunching electrous of the projected beam. matching impedance terminations at both ends of said first wave guide means, a second wave guide means capable of broad band wave transmission. when Yterminated at both ends in matching impedances, said second wave guide means extending lengthwise along the path of the beam in the portion thereof more remote from the beam projecting means in 'ansi-gy transfer relation to the beam -fcr absorblooking in direction towardthe matching impedance-terminations at both ends of said second wave guide means, whereby the broad band capabilities of both said wave guide means aresubstantially realized.

8. An electron bm translating device -comprising an electron beam source. beam prolectmg means, a iirst repetitive band pass i illus structure forming .a wave guide extending lengthwise along the path ot the projected beam tor a distance equal to several wavelengths of'a wave to be transmitted; ysaid wave guide being located .adjacent the portion of the beampath nearest the laid beam projecting means, wherebyelectrons are caused to become hunched in said beam, impedance terminations matched to said nrst wave guide connected thereto at both ends thueof, a second repetitive band-pass filter structure forming a waveguide extending lengthvwiso Aalong the path of the projected beam for a distance of several wavelengths in a portionof the beam path more remote from mid beam projecting means than said ilrst wave guide for a distance of several wavelengths in encrgyytranb fer relation with the beam, whereby the beam induces a wave in said second wave guide, and impedance terminations matched to said .second wave guide connected thereto 'at both 4crisis thereof.

9. A broad band electrical amplifier comprising a hollow pipe wave guide, a plurality of transverse bame plates therein, each of said baille plates .having an aperture, means includingf'a cathode and an anode for producing a beamof charged particles directed along a path extending lengthwise along said wave guide andv palsing through the said apertures in said -bae plates. means coupled to the said wave guide to impress wavesof a band of frequencies to `be ampliiied on said wave guide at the end thereof that is nearest the cathode, said wave impr means being matched to said wave guide and apertured baille plate structure in impedance vover substantially the whole of said frequency Vband and an output circuit for ampliiled waves connected to said structure at the end thereof that is mcstfremote from the cathode, said loutput circuit being matched to said structure over substantially the whole oi' said frequency band.

i0. A broad band electrical amplifier comprising a source of charged particles, projecting means for forming particles from said source into vl beam, s vhand-pass filter structure of elongated form extding. l along the path of the projected beam in'enargy transfer relation thoreto, said filter comprising a hollow pipe wave guide having a plurality of spaced -tr balie plates -thenin,eaclr of said baille plates having an aperture, which apertures are aligned, .and the ltcr being mounted in position to acsaid beam of lcharged particles within said aligned apertures. said tilter having an initial portion nearest the projecting means tor modulating said-beam in Kaccordance with traveling waves in said initial portion, and having .a nnal portion more remote from said projecting means in which waves may be induced by 4the beam so modulated, means coupled to the said initial lter portion to impress waves of the Vband oi' frequencies to be amplified upon said initial filter portion atthe -end thereof ythat is nearest the projecting means, said wave impr -means having its impedance substantially equal to the characteristic-impedance of the filter over mbstantiaily thexhale ofthe frequency tandis! 

